U.S. patent number 10,280,843 [Application Number 14/633,244] was granted by the patent office on 2019-05-07 for geared turbofan with integral front support and carrier.
This patent grant is currently assigned to UNITED TECHNOLOGIES CORPORATION. The grantee listed for this patent is United Technologies Corporation. Invention is credited to William G. Sheridan.
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United States Patent |
10,280,843 |
Sheridan |
May 7, 2019 |
Geared turbofan with integral front support and carrier
Abstract
A gas turbine engine includes a fan section including a fan hub.
A speed reduction device includes a star gear system. A turbine
section is connected to the fan section through the speed reduction
device. A first fan bearing for supporting rotation of the fan hub
is connected forward of the speed reduction device. A second fan
bearing for supporting rotation of the fan hub is connected aft of
the speed reduction device. A first outer race of the first fan
bearing is attached to the fan hub.
Inventors: |
Sheridan; William G.
(Southington, CT) |
Applicant: |
Name |
City |
State |
Country |
Type |
United Technologies Corporation |
Hartford |
CT |
US |
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Assignee: |
UNITED TECHNOLOGIES CORPORATION
(Farmington, CT)
|
Family
ID: |
52633138 |
Appl.
No.: |
14/633,244 |
Filed: |
February 27, 2015 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20160010562 A1 |
Jan 14, 2016 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61949331 |
Mar 7, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02C
3/107 (20130101); F01D 25/162 (20130101); F01D
5/02 (20130101); F01D 15/12 (20130101); F01D
25/16 (20130101); F02C 7/06 (20130101); F02C
7/36 (20130101); F02C 3/04 (20130101); F05D
2220/32 (20130101); F05D 2260/40311 (20130101); F05D
2230/60 (20130101) |
Current International
Class: |
F02C
7/36 (20060101); F01D 5/02 (20060101); F02C
7/06 (20060101); F02C 3/107 (20060101); F01D
25/16 (20060101); F01D 15/12 (20060101); F02C
3/04 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
US. Appl. No. 14/307,587, filed Jun. 18, 2014 Titled Load Balanced
Journal Bearing Pin. cited by applicant .
Jane's Aero-Engines, Edited by Bill Gunstron, Issue Seven, five
pages. cited by applicant .
Performance and Weight Estimates for an Advanced Open Rotor Engine,
Eric S. Hendricks and Michael T. Tong, NASA/TM-2012-217710,
AIAA-2012-3911, Sep. 2012. cited by applicant .
Ciepluch et al., "Quiet, Powered-Lift Propulsion," NASA Conference
Publication 2077, Nov. 14-15, 1978 (429 pages)--Broken down to
Report 1 through Report 8. cited by applicant .
Extended European Search Report for European Application No.
15158231.9 dated Jul. 28, 2015. cited by applicant .
European Examination Report for European Application No. 15158231.9
dated Dec. 15, 2016. cited by applicant.
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Primary Examiner: Sutherland; Steven
Attorney, Agent or Firm: Carlson, Gaskey & Olds,
P.C.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to U.S. Provisional Application
No. 61/949,331, which was filed on Mar. 7, 2014 and is incorporated
herein by reference.
Claims
What is claimed is:
1. A gas turbine engine comprising: a fan section including a fan
hub; a compressor section configured to rotate with the fan
section; a speed reduction device including a star gear system; a
turbine section connected to the fan section through the speed
reduction device; a first fan bearing for supporting rotation of
the fan hub located axially forward of the speed reduction device;
a second fan bearing for supporting rotation of the fan hub located
axially aft of the speed reduction device; and a first outer race
of the first fan bearing attached to the fan hub.
2. The gas turbine engine of claim 1 including a first inner race
of the first fan bearing fixed from rotation relative to an engine
static structure and a second inner race of the second fan bearing
fixed from rotation relative to the engine static structure.
3. The gas turbine engine of claim 1 wherein the first bearing and
the second bearing include at least one of roller bearings, ball
bearings, or tapered bearings.
4. The gas turbine engine of claim 1, wherein the star gear system
includes a sun gear, star gears, a ring gear mechanically attached
to the fan section, and a carrier fixed from rotation.
5. The gas turbine engine of claim 4, wherein each of the star
gears include a star gear bearing.
6. The gas turbine engine of claim 5, wherein the carrier includes
multiple flexible posts for mounting each of the star gears and the
star gear bearing.
7. The gas turbine engine of claim 1 wherein an inner race of a
first bearing is fixed from rotation relative to a carrier and the
carrier is fixed from rotation relative to an engine static
structure.
8. The gas turbine engine of claim 1 wherein the speed reduction
device is located radially in from a first compressor and the speed
reduction device is axially aligned with the first compressor.
9. The gas turbine engine of claim 1 including a carrier fixed from
rotation relative to an engine static structure without a static
flexible mount.
10. The gas turbine engine of claim 1 wherein the speed reduction
device is axially aligned with the compressor section.
11. The gas turbine engine of claim 1 including a rotating
compartment wall configured to rotate with the compressor section
and form a seal with an engine static structure.
12. The gas turbine engine of claim 1 wherein the first fan bearing
is at least partially axially aligned with a fan blade of the fan
section.
13. The gas turbine engine of claim 1 wherein the compressor
section includes a five stage low pressure compressor.
14. The gas turbine engine of claim 1 wherein the second fan
bearing includes a second outer race and the first outer race and
the second outer race are fixed relative to the fan hub and rotate
with the fan hub in the same direction.
15. A fan drive gear module comprising a sun gear; a multitude of
star gears surrounding the sun gear rotating on star gear bearings;
a carrier supporting the multitude of star gears and directly
contacting each of the star gear bearings, the carrier is
configured to support a fan hub with a first fan bearing located on
a first side of the carrier and a second fan bearing located on a
second opposite side of the carrier, wherein the carrier is
configured to be fixed from rotation relative to an engine static
structure without a static flexible mount; and a first outer race
of the first fan bearing and a second outer race of the second fan
bearing are fixed relative to the fan hub and rotate with the fan
hub in the same direction.
16. The fan drive gear module of claim 15 wherein the carrier
includes multiple flexible posts for mounting each of the multitude
of star gears and the star gear bearings.
17. The fan drive gear module of claim 15 including a ring gear
fixed relative to the fan hub.
18. A method of designing a gas turbine engine comprising: coupling
a speed reduction device between a fan hub and a low pressure
turbine drive shaft; positioning a first fan bearing forward of the
speed reduction device, wherein a first outer race of the first fan
bearing is fixed relative to a fan hub and rotates with the fan hub
relative to an engine static structure; and positioning a second
fan bearing aft of the speed reduction device and an outer race of
the second fan bearing is fixed relative to the fan hub and rotates
in the same rotational direction as the first outer race.
19. The method of claim 18 including positioning a first inner race
of the first fan bearing and a second inner race of the second fan
bearing are fixed from rotation relative to the engine static
structure.
20. The method of claim 18 including fixing a ring gear from the
speed reduction device relative to the fan hub to allow the ring
gear to rotate with the fan hub.
Description
BACKGROUND
A gas turbine engine typically includes a fan section, a compressor
section, a combustor section and a turbine section. Air entering
the compressor section is compressed and delivered into the
combustion section where it is mixed with fuel and ignited to
generate a high-energy exhaust gas flow. The high-energy exhaust
gas flow expands through the turbine section to drive the
compressor and the fan section. The compressor section typically
includes low and high pressure compressors, and the turbine section
includes low and high pressure turbines.
A speed reduction device such as an epicyclical gear assembly may
be utilized to drive the fan section such that the fan section may
rotate at a speed different than the turbine section so as to
increase the overall propulsive efficiency of the engine. In such
engine architectures, a shaft driven by one of the turbine sections
provides an input to the epicyclical gear assembly that drives the
fan section at a reduced speed such that both the turbine section
and the fan section can rotate at closer to optimal speeds.
The epicyclical gear assembly includes bearings that support
rotation of gears. Loads incurred during operation can disrupt a
desired relative alignment between gears and therefore the gear
assembly may be supported on structures designed to accommodate
such loads.
Although geared architectures improve propulsive efficiency, they
present different challenges that can reduce any efficiency gains.
Accordingly, turbine engine manufacturers continue to seek further
improvements to engine performance including improvements to
thermal, transfer and propulsive efficiencies.
SUMMARY
In one exemplary embodiment, a gas turbine engine includes a fan
section including a fan hub. A speed reduction device includes a
star gear system. A turbine section is connected to the fan section
through the speed reduction device. A first fan bearing for
supporting rotation of the fan hub is connected forward of the
speed reduction device. A second fan bearing for supporting
rotation of the fan hub is connected aft of the speed reduction
device. A first outer race of the first fan bearing is attached to
the fan hub.
In a further embodiment of the above, a compressor section is
configured to rotate with the fan section.
In a further embodiment of any of the above, a first inner race of
the first fan bearing is connected to a static structure and a
second inner race of the second fan bearing is connected to a
static structure.
In a further embodiment of any of the above, the first bearing and
the second bearing include at least one of roller bearings, ball
bearings, or tapered bearings.
In a further embodiment of any of the above, the gas turbine engine
includes a high pressure compressor with a compression ratio of at
least 20:1.
In a further embodiment of any of the above, the gas turbine engine
includes a low pressure compressor with a compression ratio of at
least 2:1.
In a further embodiment of any of the above, the gas turbine engine
includes a fan by pass ratio greater than 10.
In a further embodiment of any of the above, the star gear system
includes a sun gear, star gears, a ring gear mechanically attached
to the fan section, and a carrier fixed from rotation.
In a further embodiment of any of the above, each of the star gears
include a star gear bearing.
In a further embodiment of any of the above, the carrier includes
multiple flexible posts for mounting each of the star gears and the
star gear bearing.
In a further embodiment of any of the above, the inner race of the
first bearing is attached to a carrier that is fixed to an engine
static structure.
In a further embodiment of any of the above, the speed reduction
device is located radially in from a first compressor and the speed
reduction device is axially aligned with the first compressor.
In a further embodiment of any of the above, a carrier is attached
to an engine static structure without a static flexible mount.
In another exemplary embodiment, a fan drive gear module includes a
sun gear. A multitude of star gears surround the sun gear. A
carrier supports the multitude of star gears. The carrier is
configured to support a fan hub with a first fan bearing located on
a first side of the carrier and a second fan bearing located on a
second opposite side of the carrier. The carrier is configured to
be attached to a static engine structure without a static flexible
mount. An outer race of at least one of the first fan bearing and
the second fan bearing is configured to connect to the fan hub.
In a further embodiment of the above, each of the multitude of star
gears include a star gear bearing.
In a further embodiment of any of the above, the carrier includes
multiple flexible posts for mounting each of the multitude of star
gears and the star gear bearing.
In a further embodiment of any of the above, a ring gear is
configured to be attached to the fan hub.
In another exemplary embodiment, a method of designing a gas
turbine engine includes coupling a speed reduction device between a
fan hub and a low pressure turbine drive shaft and positioning a
first fan bearing forward of the speed reduction device. A first
outer race of the first fan bearing is attached to a fan hub. A
second fan bearing is positioned aft of the speed reduction
device.
In a further embodiment of any of the above, the method includes
positioning of a first inner race of the first fan bearing and a
second inner race of the second fan bearing is attached to a static
structure.
In a further embodiment of any of the above, the method includes
connecting a ring gear from the speed reduction device to the fan
hub.
The various features and advantages of this disclosure will become
apparent to those skilled in the art from the following detailed
description. The drawings that accompany the detailed description
can be briefly described as follows.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of an example gas turbine engine.
FIG. 2 is a schematic view of an example geared architecture.
FIG. 3 is a schematic view of another example geared
architecture.
DETAILED DESCRIPTION
FIG. 1 schematically illustrates a gas turbine engine 20. The gas
turbine engine 20 is disclosed herein as a two-spool turbofan that
generally incorporates a fan section 22, a compressor section 24, a
combustor section 26 and a turbine section 28. Alternative engines
might include an augmentor section (not shown) among other systems
or features. The fan section 22 drives air along a bypass flow path
B in a bypass duct defined within a nacelle 15, while the
compressor section 24 drives air along a core flow path C for
compression and communication into the combustor section 26 then
expansion through the turbine section 28. Although depicted as a
two-spool turbofan gas turbine engine in the disclosed non-limiting
embodiment, it should be understood that the concepts described
herein are not limited to use with two-spool turbofans as the
teachings may be applied to other types of turbine engines
including three-spool architectures.
The exemplary engine 20 generally includes a low speed spool 30 and
a high speed spool 32 mounted for rotation about an engine central
longitudinal axis A relative to an engine static structure 36 via
several bearing systems 38. It should be understood that various
bearing systems 38 at various locations may alternatively or
additionally be provided, and the location of bearing systems 38
may be varied as appropriate to the application.
The low speed spool 30 generally includes an inner shaft 40 that
interconnects a fan 42, a first (or low) pressure compressor 44 and
a first (or low) pressure turbine 46. The inner shaft 40 is
connected to the fan 42 through a speed change mechanism, which in
exemplary gas turbine engine 20 is illustrated as a geared
architecture 48 to drive the fan 42 at a lower speed than the low
speed spool 30. The high speed spool 32 includes an outer shaft 50
that interconnects a second (or high) pressure compressor 52 and a
second (or high) pressure turbine 54. A combustor 56 is arranged in
exemplary gas turbine 20 between the high pressure compressor 52
and the high pressure turbine 54. A mid-turbine frame 57 of the
engine static structure 36 is arranged generally between the high
pressure turbine 54 and the low pressure turbine 46. The
mid-turbine frame 57 further supports bearing systems 38 in the
turbine section 28. The inner shaft 40 and the outer shaft 50 are
concentric and rotate via bearing systems 38 about the engine
central longitudinal axis A which is collinear with their
longitudinal axes.
The core airflow is compressed by the low pressure compressor 44
with a compression ratio of at least 2:1 then the high pressure
compressor 52, mixed and burned with fuel in the combustor 56, then
expanded over the high pressure turbine 54 and low pressure turbine
46. The mid-turbine frame 57 includes airfoils 59 which are in the
core airflow path C. The turbines 46, 54 rotationally drive the
respective low speed spool 30 and high speed spool 32 in response
to the expansion. It will be appreciated that each of the positions
of the fan section 22, compressor section 24, combustor section 26,
turbine section 28, and fan drive gear system 48 may be varied. For
example, gear system 48 may be located aft of combustor section 26
or even aft of turbine section 28, and fan section 22 may be
positioned forward or aft of the location of gear system 48.
The engine 20 in one example is a high-bypass geared aircraft
engine. In a further example, the engine 20 bypass ratio is greater
than about six (6), with an example embodiment being greater than
about ten (10), the geared architecture 48 is an epicyclic gear
train, such as a planetary gear system or other gear system, with a
gear reduction ratio of greater than about 2.3 and the low pressure
turbine 46 has a pressure ratio that is greater than about five. In
one disclosed embodiment, the engine 20 bypass ratio is greater
than about ten (10:1), the fan diameter is significantly larger
than that of the low pressure compressor 44, and the low pressure
turbine 46 has a pressure ratio that is greater than about five
5:1. Low pressure turbine 46 pressure ratio is pressure measured
prior to inlet of low pressure turbine 46 as related to the
pressure at the outlet of the low pressure turbine 46 prior to an
exhaust nozzle. The geared architecture 48 may be an epicycle gear
train, such as a planetary gear system or other gear system, with a
gear reduction ratio of greater than about 2.3:1. It should be
understood, however, that the above parameters are only exemplary
of one embodiment of a geared architecture engine and that the
present invention is applicable to other gas turbine engines
including direct drive turbofans.
A significant amount of thrust is provided by the bypass flow B due
to the high bypass ratio. The fan section 22 of the engine 20 is
designed for a particular flight condition--typically cruise at
about 0.8 Mach and about 35,000 feet. The flight condition of 0.8
Mach and 35,000 ft (10,668 meters), with the engine at its best
fuel consumption--also known as "bucket cruise Thrust Specific Fuel
Consumption (`TSFC`)"--is the industry standard parameter of lbm of
fuel being burned divided by lbf of thrust the engine produces at
that minimum point. "Low fan pressure ratio" is the pressure ratio
across the fan blade alone, without a Fan Exit Guide Vane ("FEGV")
system. The low fan pressure ratio as disclosed herein according to
one non-limiting embodiment is less than about 1.45. "Low corrected
fan tip speed" is the actual fan tip speed in ft/sec divided by an
industry standard temperature correction of [(Tram.degree.
R)/(518.7.degree. R)].sup.0.5. The "Low corrected fan tip speed" as
disclosed herein according to one non-limiting embodiment is less
than about 1150 ft/second (350.5 meters/second).
FIG. 2 illustrates the inner shaft 40 driving the geared
architecture 48 to turn the fan 42 and the low pressure compressor
44 together at the same rotational speed. The inner shaft 40 is
connected with a sun gear 60 in the geared architecture 48. The sun
gear 60 is surrounded by star gears 62 mounted on star gear bearing
assemblies 64 attached to a static carrier 66. The static carrier
66 allows the star gears 62 to rotate around an axis of each star
gear 62 but not around and engine axis A. The static carrier 66 is
fixed relative to the engine static structure 36 on the gas turbine
engine 20.
The geared architecture 48 is located radially inward and axially
aligned with the low pressure compressor 44 to shorten the overall
length of the gas turbine engine 20.
A fan hub 68 is supported by a forward fan bearing 70 and an aft
fan bearing 72. The forward fan bearing 70 includes an inner race
74 fixed to the static carrier 66 and an outer race 76 fixed to the
fan hub 68. The forward fan bearing 70 supports radial and thrust
loads from a forward end of the fan hub 68.
The aft fan bearing 72 includes an inner race 78 attached to the
static carrier 66, which is connected with the engine static
structure 36, and an outer race 80 is attached to a rotating aft
support 82. The aft fan bearing 72 supports an aft end of the fan
hub 68 and carries radial loads from the fan 42.
A rotatable ring gear 84 turns the fan hub 68 and the low pressure
compressor 44 at the same rotational speed. A rotating compartment
wall 86 extends from the rotating aft support 82 and is sealed
against the engine static structure 36 with an oil seal 88.
Scavenged oil passes through holes 90 extending through the ring
gear 84, the rotating aft support 82, and the engine static
structure 36 to direct oil towards the forward and aft fan bearing
70 and 72 and the geared architecture 48. A rotating cover 92 aids
in retaining and directing the oil towards the forward fan bearing
70, the aft fan bearing 72, and the geared architecture 48 and to
prevent the need for carbon seals.
FIG. 3 illustrates another example geared architecture 148. The
geared architecture 148 is similar to the geared architecture 48
shown in FIG. 2 except where shown in FIG. 3 or described
below.
A static carrier 110 includes an oil baffle 100 extending from a
forward end and a cylindrical support 102 for supporting the
forward fan bearing 70. An oil feed tube 106 supplies oil to the
static carrier 110 and the rest of geared architecture 148. A
multitude of flexible shafts 112 extend from the static carrier 110
to support the star gears 62 and the respective star gear bearing
assemblies 64. The flexibility of the shafts 112 support torsional
loads from the star gears 62 and star gear bearing assemblies 64
and allow the star gears 62 to be isolated from the engine static
structure 36 such that a static flexible mount is not necessary to
mount the geared architecture 148.
The forward fan bearing 70 in this example includes a roller
bearing with the inner race 74 mounted to the cylindrical support
102 and the outer race 76 rotatably attached to the fan hub 68
through a hub support 104. Although a roller bearing is illustrated
in this example for the forward fan bearing 70, a ball bearing or a
tapered bearing could also be utilized.
The aft fan bearing 72, such as a ball bearing, is mounted on an
aft side of the geared architecture 148 opposite from the forward
bearing 70. Although a ball bearing is illustrated in this example
for the aft fan bearing 72, a roller bearing or a tapered bearing
could also be utilized.
The forward fan bearing 70 and the aft fan bearing 72 straddle the
geared architecture 148 to greatly reduce misalignment imparted on
the geared architecture 148. This eliminates the need for a
flexible coupling on the geared architecture 148 to combat
misalignment forces acting on the gears.
An inner shaft bearing 114 attached to the engine static structure
36 supports a forward end of the inner shaft 40 and carries both
radial and thrust loads. Since the fan 42 imparts a forward thrust
load and low pressure turbine 46 imparts an aft thrust load on the
inner shaft 40, the opposing loads are generally cancelled out by
the aft fan bearing 72 and the inner shaft bearing 114 both being
attached to the engine static structure 36.
The gas turbine engine 20 is designed by attaching the geared
architecture 48 or 148 device to the fan hub 68 and the inner shaft
40. The forward fan bearing 70 is positioned forward of the geared
architecture 48 or 148 with the first outer race 76 connected to
the fan hub 68. The aft fan bearing 72 is positioned aft of the
geared architecture 48 or 148. The inner race 74 and the inner race
78 are attached to the static carrier (66 or 110). The ring gear 85
from the geared architecture 48 or 148 is connected to the fan hub
68.
The preceding description is exemplary rather than limiting in
nature. Variations and modifications to the disclosed examples may
become apparent to those skilled in the art that do not necessarily
depart from the essence of this disclosure. The scope of legal
protection given to this disclosure can only be determined by
studying the following claims.
* * * * *